Method of making diarlysilanediol containing polymers, polymer compositions and articles containing such polymers

ABSTRACT

A method of making a polymer with stable Mooney viscosity and molecular weight is described. A conjugated diolefin is reacted in a hydrocarbon solvent in the presence of an initiator to form a polymer. After forming the polymer, alkoxy silane terminal functionalizing groups are bonded to the polymer. A mixture of at least one of a first stabilizing agent having the formula (R) 4-n Si(OH) n  wherein R is a C 1  to C 18  alkyl, C 1  to C 18  alkyl group containing a heteroatom such as nitrogen or oxygen, C 4  to C 8  cycloalkyl, or C 6  to C 18  aromatic group, and a at least one of a second stabilizing agents having the formula (R) 2 Si(OH) 2  wherein R is an aryl group, is then added to the polymer, optionally in the presence of hydrocarbon oil. The polymer is then desolvatized, resulting in a polymer with stable Mooney viscosity and molecular weight, even over prolonged periods of time. Compositions and articles containing the polymer are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application may relate to subject matter disclosed in one ormore of U.S. patent application Ser. No. 61/656,144 entitled “Method ofMaking Polymers, Polymer Compositions and Articles Containing SuchPolymers”, 61/656,136 entitled “Method of Making Alkoxysilane StabilizedPolymers, Polymer Compositions, and Articles Containing Such Polymers”,61/656,139 entitled “Method of Making Iminosilane Stabilized Polymers,Polymer Compositions, and Articles Containing Such Polymers”, and61/656,124 entitled “Method of Making Base Stabilized Polymers, PolymerCompositions and Articles Containing Such Polymers”. Each of theaforementioned applications is assigned to an entity common hereto andshares an inventor common hereto. Further, the entirety of each andevery one of the aforementioned applications is incorporated herein byreference for all purposes.

TECHNICAL FIELD

The field of art to which this invention generally pertains isconjugated diolefin polymers, methods of producing the same, andcompositions and articles containing such polymers.

BACKGROUND

There is a constant search in the area of elastomeric polymers, such asstyrene-butadiene rubbers, to control Mooney viscosity (ML/T80). Note,for example U.S. Pat. Nos. 5,659,056; 6,255,404; 6,393,167; 7,342,070;and published patent application No. 2009/0163668, the disclosures ofwhich are incorporated by reference. Mooney viscosity creep with aginghas become even more pronounced with the movement from batch tocontinuous polymerization.

Advantageous properties have been imparted to polymers which aretypically terminated using a number of different functional compounds,including silane containing compounds, to yield silane end-cappedpolymers. Note also, for example, U.S. Pat. Nos. 3,244,664 and4,185,042, the disclosures of which are incorporated by reference. Thisalkoxysilane termination may also result in an increase in the Mooneyviscosity of the treated polymer. However, upon the subsequent processof desolventization of the alkoxysiloxane terminated polymers throughthe use of either steam or heated water, an even larger increase inMooney viscosity often occurs during the hydrolysis of thealkoxysiloxane end groups such as pendant —SiOR groups on the siloxaneend groups, thereby leading to coupling of the polymer via formation ofSi—O—Si bonds between two end groups. Accordingly, many of the processestried in the past do not actually prevent an increase in Mooneyviscosity, but only slow the rate of the hydrolysis reaction and,therefore, the rate of coupling of the polymer. Over a period of time,for example during storage, the slow hydrolysis of the end groups willoccur, thereby continuing the problem of increased Mooney viscosity andcoupling of the alkoxysilane terminated polymers with aging.

Thus, while attempts have been made to reduce the rate of the hydrolysisreaction that results in the coupling of the alkoxysilane end groups ofthe polymers, the art has not provided a means or method by which tostabilize the polymer upon aging and essentially stop or slow down thecoupling of the alkoxysilane terminated polymers over time.

BRIEF SUMMARY OF THE INVENTION

The present invention solves the above-mentioned problems through theuse of methods for controlling the increase in Mooney viscosity andmolecular weight of functionalized polymers, particularly during aging,e.g., storage over long periods of time. The methods involve reacting aconjugated diolefin in a hydrocarbon solvent in the presence of aninitiator to form a polymer. Alkoxy silane terminal functionalizinggroups may then be bonded to the polymer. A mixture of stabilizingagents is then added to the polymer, including at least one of a firststabilizing agents having the formula (R)_(4-n)Si(OH)_(n) where R is aC₁ to C₁₈ alkyl, C₁ to C₁₈ alkyl group containing a heteroatom such asnitrogen or oxygen, C₄ to C₈ cycloalkyl, or C₆ to C₁₈ aromatic group,and at least one of a second stabilizing agents having the formula(R)₂Si(OH)₂ wherein R is a C₆ to C₁₈ aromatic group. As demonstrated bythe included examples, n typically has a value of 1. The polymer is thentypically desolvatized, resulting in a polymer with stable Mooneyviscosity.

Aspects of the invention include: the first stabilizing agent being atrialkylsilanol, a triarylsilanol, or mixtures thereof; the secondstabilizing agent being at least one diarylsilanediol; the firststabilizing agent being a triphenylsilanol; the second stabilizing agentbeing a diphenylsilanediol; the desolvatizing being performed by drumdrying, direct drying, or steam desolvatizing; adding the stabilizingagent with the polymer optionally in the presence of hydrocarbon oil;the initiator being a butyl lithium; the hydrocarbon solvent being oneor more hexanes; the conjugated diolefin being a 1,3-butadiene; thepolymerizing step including the presence of an aromatic vinyl compound;the aromatic vinyl compound being a styrene; and the hydrocarbon oilbeing a black oil.

Aspects of the invention include: drying the polymer after steamdesolvatizing; the polymers produced according to methods of thisinvention; rubber compositions containing fillers and the polymersproduced according to methods of this invention; rubber compositionshaving a 65° C. tan delta lower than the 65° C. tan delta of a rubbercompositions with either the first stabilizing agent or the secondstabilizing agent used alone; and tires containing rubber compositionsdisclosed herein.

These and other objects, aspects, embodiments and features of theinvention will become more fully apparent when read in conjunction withthe following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the various embodiments of the presentinvention only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of the invention. In this regard, noattempt is made to show details of the invention in more detail than isnecessary for a fundamental understanding of the invention, thedescription making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

The present invention will now be described by reference to moredetailed embodiments, with occasional reference to the accompanyingdrawings. This invention may, however, be embodied in different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The terminology used in thedescription of the invention herein is for describing particularembodiments only and is not intended to be limiting of the invention. Asused in the description of the invention and the appended claims, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Allpublications, patent applications, patents, and other referencesmentioned herein are expressly incorporated by reference in theirentirety.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present invention. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should be construed in light of the number of significantdigits and ordinary rounding approaches.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Every numerical range given throughoutthis specification will include every narrower numerical range thatfalls within such broader numerical range, as if such narrower numericalranges were all expressly written herein.

Additional advantages of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. It is to beunderstood that both the foregoing general description and the followingdetailed description are exemplary and explanatory only and are notrestrictive of the invention, as claimed.

Attempts to address Mooney viscosity deterioration in polymers aredescribed, for example, in U.S. Pat. No. 5,659,056, which describes aprocess to treat the polymer prior to desolventization with a C₁ to C₁₂aliphatic or C₆ to C₁₂ cycloaliphatic or aromatic carboxylic acidviscosity stabilizing agent soluble in the solvent used to prepare thepolymer. U.S. Pat. No. 6,255,404 describes a method for stabilizing theMooney viscosity of a siloxane-terminated polymer having at least onehydrolyzable substituent on the siloxane end group with an alkyltrialkoxysilane viscosity stabilizing agent. U.S. Pat. No. 6,369,167teaches improving polymer properties by reacting the terminal end groupsof the polymer with a compound having alkylideneamino groups. U.S. Pat.No. 7,342,070 teaches improving polymer properties by bonding a primaryamino group and an alkoxysilyl group to the polymer chain. And U.S. Pub.No. 2009/0163668 describes a method of improving polymer properties byreacting the active end groups of the polymer with a specific lowmolecular weight compound having a secondary amino group in which ahydrogen atom is substituted with a triorgano-substituted silyl group,an organic group having an N atom not adjacent to the N atom of thesecondary amino group, and at least one alkoxysilyl group or a specificlow molecular compound containing a heterocycle having a secondary aminogroup in which a hydrogen atom is substituted with atriorgano-substituted silyl group and at least one alkoxysilyl group.Alkoxysilane-terminated polymers are also well known in the art and havebeen prepared, for example, as described in U.S. Pat. No. 6,255,404 toHogan, the disclosure of which is incorporated by reference. Issuesstill exist, however, with controlling Mooney viscosity and molecularweight, especially over time, for example, in long term storage.

The present invention not only produces polymers with acceptable Mooneyviscosity levels and molecular weight as produced, but controls thesevalues over time, including over long term storage. The process of thepresent invention is particularly applicable to any polymer having aterminal functionalized end group having a hydrolyzable substituentwhich, when hydrolyzed, is subject to cross linking with otherhydrolyzed groups. The hydrolyzable group is typically a pendant —SiORgroup wherein R is an alkyl, cycloalkyl, or aromatic group capable ofcoupling with a like or similar pendant —SiOR group to form an Si—O—Sibond.

Polymers that can be stabilized in accordance with the process of thepresent invention can be any conjugated diolefins known in the artincluding polybutadiene, polyisoprene, and the like, and copolymersthereof with monovinyl aromatics such as styrene, alpha methyl styreneand the like, and trienes such as myrcene. Thus, the polymers includediene homopolymers and copolymers thereof with aromatic vinyl compounds.Exemplary diene homopolymers are those prepared from diolefin monomershaving from about 4 to about 12 carbon atoms. Exemplary vinyl aromaticpolymers are those prepared from monomers having from about 8 to about20 carbon atoms.

Preferred polymers include diene homopolymers such as polybutadiene andpolyisoprene and copolymers such as styrene butadiene rubber (SBR).Polymers and copolymers can comprise from 100 to about 20 percent byweight of diene units and from 0 to about 80 percent by weight ofmonovinyl aromatic hydrocarbon or triene units, totaling 100 percent.The copolymers may be random copolymers or block copolymers. Blockcopolymers include, but are not limited to,poly(styrene-butadiene-styrene), which are thermoplastic polymers. Thepolymers utilized and treated in accordance with the process of thepresent invention display utility in a number of applications,including, for example, use in the manufacture of tires.

The polymers employed in the practice of this invention can be preparedby employing any polymerization techniques. These techniques include,but are not limited to, cationic and anionic techniques, transitionmetal or coordination catalyst techniques, emulsion techniques, etc.Similarly, any organic alkali metals and/or the organic alkali earthmetals may be used in the polymerization process of the presentinvention, including alkyllithiums such as n-butyllithium,sec-butyllithium and t-butyllithium, alkylenedilithiums such as1,4-dilithiobutane, phenyllithium, stilbenelithium, lithiumnaphthalene,sodiumnaphthalene, potassiumnaphthalene, n-butylmagnesium,n-hexylmagnesium, ethoxycalcium, calcium stearate, t-butoxystrontium,ethoxybarium, isopropoxybarium, ethylmercaptobarium, t-butoxybarium,phenoxybarium, diethylaminobarium, and barium stearate.

Polymerization of the polymers may be conducted in the presence of anorganolithium anionic initiator catalyst composition. The organolithiuminitiator employed may be any anionic organolithium initiators useful inthe polymerization of 1,3-diene monomers. In general, the organolithiumcompounds include hydrocarbon containing lithium compounds of theformula R(Li)_(x) wherein R represents hydrocarbon groups containingfrom one to about 20 carbon atoms, and preferably from about 2 to about8 carbon atoms, and x is an integer from 1 to 2. Although thehydrocarbon group is preferably an aliphatic group, the hydrocarbongroup may also be cycloaliphatic or aromatic. The aliphatic groups maybe primary, secondary, or tertiary groups although the primary andsecondary groups are preferred. Examples of aliphatic hydrocarbyl groupsinclude methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl,n-amyl, sec-amyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-nonyl,n-dodecyl, and octa-decyl. The aliphatic groups may contain someunsaturation such as allyl, 2-butenyl, and the like. Cycloalkyl groupsare exemplified by cyclohexyl, methylcyclohexyl, ethylcyclohexyl,cycloheptyl, cyclopentylmethyl, and methylcyclopentylethyl. Examples ofaromatic hydrocarbyl groups include phenyl, tolyl, phenylethyl, benzyl,naphthyl, phenyl cyclohexyl, and the like.

Specific examples of organolithium compounds which are useful as anionicinitiators in the polymerization of conjugated dienes in accordance withthe process of the present invention include, but are not limited to,butyl lithium, n-butyl lithium, n-propyl lithium, isobutyl lithium,sec-butyl lithium, tertiary butyl lithium, amyl-lithium, and cyclohexyllithium. Mixtures of different lithium initiator compounds also can beemployed preferably containing one or more lithium compounds such asR(Li)_(x), R and x as defined above. Other lithium catalysts which canbe employed alone or in combination with the hydrocarbyl lithiuminitiators are tributyl tin lithium, lithium dialkyl amines, lithiumdialkyl phosphines, lithium alkyl aryl phosphines and lithium diary′phosphines. The preferred organolithium initiator is n-butyl lithium andin situ produced lithium hexamethylenimide initiator.

The amount of initiator required to effect the desired polymerizationcan be varied over a wide range depending upon a number of factors suchas the desired polymer molecular weight, the desired 1,2- and1,4-content of the conjugated diene, and the desired physical propertiesfor the polymer produced. In general, the amount of initiator utilizedmay vary from as little as 0.2 millimole of lithium per 100 grams ofmonomers up to about 100 millimoles of lithium per 100 grams ofmonomers, depending upon the desired polymer molecular weight (typically1,000 to 100,000,000 number average molecular weight).

The polymerizations of the present invention may be conducted in aninert solvent and would consequently be solution polymerizations. Theterm “inert solvent” means that the solvent does not enter into thestructure of the resulting polymer, does not adversely affect theproperties of the resulting polymer, and does not adversely affect theactivity of the catalyst employed. Suitable inert solvents includehydrocarbon solvents which may contain aliphatic, aromatic orcycloaliphatic hydrocarbons such as hexane, pentane, toluene, benzene,cyclohexane and the like. Ethers such as tetrahydrofuran and tertiaryamines such as triethylamine and tributylamine may also be used assolvents, but these will modify the polymerization as to styrenedistribution, vinyl content and rate of reaction. The preferred solventsare aliphatic hydrocarbons and of these solvents, hexane is particularlypreferred, including blends and mixtures of hexanes, e.g., linear andbranched, including such things as cyclohexane alone or mixed with otherforms of hexane.

Polymerization conditions such as temperature, pressure and time arewell known in the art for polymerizing the monomers as described withthe anionic initiator as described. For example, for illustrativepurposes only, the temperature employed in the polymerization isgenerally not critical and may range from about −60° C. to about 150° C.Preferred polymerization temperatures may range from about 25° C. toabout 130° C. for a polymerization time of a few minutes to up to 24hours or more, and employing pressures generally sufficient to maintainpolymerization admixtures substantially in the liquid phase, preferablyat or near atmospheric pressure, depending on the temperature and otherreaction parameters. Polymerization of any of the above-identifiedmonomers in the presence of an organolithium initiator results in theformation of a “living” polymer. The lithium proceeds to move down thegrowing chain as polymerization continues. Throughout formation orpropagation of the polymer, the polymeric structure may be anionic andliving. In other words, a carbon anion is present. A new batch ofmonomer subsequently added to the reaction can add to the living ends ofthe existing chains and increase the degree of polymerization. A livingpolymer, therefore, may include a polymeric segment having an anionicreactive end. Reference to anionically polymerized polymers oranionically polymerized living polymers refers to those polymersprepared by anionic polymerization techniques.

In order to promote randomization in copolymerization and to controlvinyl content, one or more modifiers may optionally be added to thepolymerization ingredients. Amounts range from 0 to about 90 or moreequivalents per equivalent of lithium. Compounds useful as modifiers aretypically organic and include those having an oxygen or nitrogenheteroatom and a non-bonded pair of electrons. Examples include dialkylethers of mono and oligo alkylene glycols; “crown” ethers; tertiaryamines such as tetramethyethylene diamine (TMEDA); tetrahydrofuran(THF), THF oligomers linear and cyclic oligomeric oxolanyl alkanes andthe like. Particular examples of these modifiers include potassiumt-butylamylate and 2,2′-di(tetrahydrofuryl) propane. These modifiers arefurther described in U.S. Pat. No. 4,429,091, the disclosure of which inincorporated by reference.

Polymerization is begun by charging a blend of the monomer(s) andsolvent to a suitable reaction vessel, followed by the addition of themodifier(s) and the initiator solution previously described. Theprocedure is carried out under anhydrous, anaerobic conditions. Thereactants may be heated to a temperature of from about 23° C. to about120° C., and are typically agitated for about 0.15 to about 24 hours.After polymerization is complete, the product may be removed from theheat and terminated with a functional end group as is conventionallydone in the art, although termination could also be done without removalof heat. Prior to terminating the polymerization reaction with afunctional end group, a coupling agent may be added to thepolymerization reaction to increase the Mooney viscosity to a desiredrange. Tin coupling agents such as tin tetrachloride (SnCl₄) are wellknown in the art and may be added in varying amounts, typically inamounts of 0 to about 0.9 mole equivalents functionality per each moleequivalent of anionic initiator depending upon the desired Mooneyviscosity of the polymer.

The functional terminated polymers described above may include anypolymer having a terminal end group in which the end group contains oneor more hydrolyzable pendant substituents. Exemplary alkoxy silaneterminal functionalizing groups bonded to polymers are silane terminatedpolymers represented by the following formula:

wherein X may be present or not present and represents a linking atom,chemical bond, or a linking group such as oxygen or sulfur, and whereinR¹ is a C₁ to C₁₈ alkyl, C₁ to C₁₈ alkyl group containing a heteroatomsuch as nitrogen or oxygen, C₄ to C₈ cycloalkyl, or C₆ to C₁₈ aromaticgroup, and R² and R³ may be the same or different and are selected fromthe group consisting of —OR¹, a C₁ to C₁₈ alkyl, C₄ to C₈ cycloalkyl, orC₆ to C₁₈ aromatic group. Preferred functionalizing agents would be oneor more of ethyl silicate, bis(3-trimethoxysilylpropyl)-n-methylamine(BTMSPMA), and 3-(1,3,-dimethylbutylidene)aminopropyltriethoxysilane(DMBAPTES), e.g., represented in the above formula by R¹ being C₂,forming an ethoxy group, R² being the same group as OR₁ and R³ being a3-(1,3-dimethylbutylidene)aminopropyl group. In addition to the formularepresentation shown above, additional polymer chains could also bebonded through the R² and/or the OR¹ positions as well.

The process of the present invention, prior to quenching, drying orremoving the solvent, e.g., by drum drying, with steam or heated water,or direct drying (e.g., List AG technology), and optionally furtherdrying the polymer, adds trialkylsilanol, and/or triarylsilanol, anddiarylsilanediol stabilizing agents, and optionally hydrocarbon oil, tothe polymer. Particularly preferred viscosity and molecular weightstabilizing agents are mixtures of triphenylsilanols anddiphenylsilanediols.

The viscosity stabilizing agents of the present invention can beemployed in varying amounts and the amount employed is particularlydependent upon the type of alkoxysilane employed since reaction with thealkoxysilane terminated polymers is dependent upon the molar ratio ofthe added silanol to the alkoxysilane terminated polymer. For example,where a triarylsilanol is used, a significant amount of the agent willbe necessary to provide a ratio which will supply a sufficiently highmolar ratio of stabilizing agent to alkoxysilane terminated polymer.Nevertheless, for the silanols, preferred amounts may range from about0.5 to about 50 mole equivalents per mole equivalent of anionicinitiator, and more preferrably, a range of from about 1 mole to about20 mole equivalents per mole equivalent of anionic initiator is desired,with 2 to 8 mole equivalents most typically used. The silanols may beadded alone or as mixtures, as well as salts of the silanols, either assalt of the silanol preformed or formed in situ, e.g., as lithium,potassium, sodium, magnesium, calcium, etc. salts. The diarylsilanediolsare typically present in amounts up to 4 equivalents, and as describedin more detail below, when added to the triphenol silanol, for example,results in a lowering of the need for amounts of both materials toobtain good Mooney control.

The viscosity stabilizing agents of the present invention react with thefunctional end groups of the polymer. However, because the Si—O—Si bondsbeing produced are between the polymer and the stabilizing agentadditive, and not between the polymers themselves, there is nosignificant increase in Mooney viscosity.

The optionally added hydrocarbon oils such as aromatic or naphthenicoils can be used. The oil used is not particularly limited, and in factany hydrocarbon oils such as those typically used with diene-basedpolymers can be used. A mineral based oil is preferably used. Ingeneral, commercially available mineral oils are mixtures of aromaticoils, alicyclic oils and aliphatic oils, and classified into thearomatic family, alicyclic family (naphthenic family) and aliphaticfamily (paraffinic family) according to the amount and ratio thereof.Any of them can be used in the present invention. However, black oil isparticularly preferred. Black oil is a relatively inexpensive,low-grade, black petroleum oil. It is typically described as liquidcrude oil or heavy fuel oil. It is commercially available and can bepurchased from Ergon under the brand name HYPRENE BO300, for example.

In addition to the viscosity stabilizing agent, an antioxidant such as2,6-di-t-butyl-4-methylphenol or butylated hydoxy toluene (BHT) may beadded in solvent (hexane) solution, as is well known in the art. Theantioxidant reduces the likelihood that Mooney viscosity stability isnot due to oxidative coupling.

Optionally, upon termination, the functional terminated polymer could bequenched, if necessary, and dried. Quenching may be conducted bycontacting the alkoxysilane terminated polymer with a quenching agentfor about 0.05 to about 2 hours at temperatures of from about 30° C. toabout 120° C. to insure complete reaction. Suitable well known quenchingagents include alcohol, water, carboxylic acids such 2-ethylhexanoicacid (EHA), acetic acid and the like. Coagulation is typically done withalcohols such as methanol or isopropanol. Alternative to, or incombination with, the step of quenching, the alkoxysilane terminatedpolymer may be drum dried as is well known in the art. The use of steamor high heat to remove solvent is also well known in the art.

The terminal functionalizing agent may be present in a molar ratio (toinitiator) of about 0.25 to 2, and preferably about 0.5 to 1. Thestabilizing agent may be present in a molar ratio to initiator of 0.5 to50, more typically 1 to 20, and preferably 2 to 8. As stated above, whenmixtures of both the first and second stabilizing agents are used, lessof both can be used, e.g., with mixture totals of about 0.1 to 20, andmore typically about 0.2 to 10 being used. The hydrocarbon oil, whenpresent, is typically present in an amount of 1 to 40 parts per hundred(phr) parts polymer, and preferably 1 to 20 phr.

While polymers according to the present invention may be produced withMooney viscosity less than 150, less than 120 is preferred, and lessthan 100 more preferred. Ideally, 40 to 80 is the most preferred targetrange. Control of increase in Mooney viscosity over time is also one ofthe real advantages of the present invention. Changes in Mooneyviscosity (increases) of less than 20 over a storage period of up to twoyears is preferred.

The invention is further illustrated by reference to the followingexamples. It will be apparent to those skilled in the art that manymodifications, both to the materials and methods, may be practicedwithout departing from the purpose and scope of the invention.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

Example 1

A 100-gallon (379 liter) reactor was charged with the following: 66.2kilograms (kg) dry hexanes, 102.3 kg of a 21.8 weight percent solutionof 1,3-butadiene in hexanes (22.3 kg, 413 mol), and 38.0 kg of a 31.0weight percent solution of styrene in hexanes (11.8 kg, 109 mol). Themixture was stirred and heated to 32° C. When the temperature target wasreached, 614 grams (g) of a 3 weight percent solution of n-BuLi inhexanes (18.4 g, 0.288 mol), 34.4 g of a 10 weight percent solution of2,2′-isopropylidene bis(tetrahydrofuran) in hexanes (0.019 mol), and19.3 g of a 15 weight percent solution of potassium t-amylate in hexanes(0.023 mol) were added. The reaction temperature reached a peak of 82.1°C. within 2 hours, at which time 43.6 g (0.143 mol, 0.50 equiv)3-(1,3,-dimethylbutylidene)aminopropyltriethoxysilane (DMBAPTES) wasadded. The reaction was stirred for 15 minutes then 6.2 g (0.028 mol,0.1 equiv) diphenylsilanediol (DPSDO) was added as a 5% solution inethanol-cyclohexane mixture. After mixing for 20 minutes, the sample wasremoved from the reactor with 1 weight percent BHT added for oxidationprotection.

Example 2

A 13-gallon (49 liter) reactor was charged with the following: 6.0kilograms (kg) dry hexanes, 10.2 kg of a 21.8 weight percent solution of1,3-butadiene in hexanes (2.2 kg, 41.3 mol), and 3.8 kg of a 31.0 weightpercent solution of styrene in hexanes (1.2 kg, 10.9 mol). The mixturewas stirred and heated to 32° C. When the temperature target wasreached, 57 grams of a 3 weight percent solution of n-BuLi in hexanes(1.7 g, 0.027 mol), 3.2 g of a 10 weight percent solution of2,2′-isopropylidene bis(tetrahydrofuran) in hexanes (0.0018 mol), and1.8 g of a 15 weight percent solution of potassium t-amylate in hexanes(0.0021 mol) were added. The reaction temperature reached a peak of79.4° C. within 2 hours, at which time 0.92 g (0.0026 mol, 0.10 equiv)of bis(3-trimethoxysilylpropyl)-n-methylamine (BTMSPMA) was added,followed 20 minutes later by 4.9 g (0.016 mol, 0.60 equiv)3-(1,3,-dimethylbutylidene)aminopropyltriethoxysilane (DMBAPTES) wasadded. The reaction was stirred for 15 minutes then 3.3 g (0.012 mol,0.42 eqiv) of triphenylsilanol (TPS) was added and then the sample wasremoved from the reactor with 1 weight percent BHT added for oxidationprotection.

Example 3

A 13-gallon (49 liter) reactor was charged with the following: 6.0kilograms (kg) dry hexanes, 10.2 kg of a 21.8 weight percent solution of1,3-butadiene in hexanes (2.2 kg, 41.3 mol), and 3.8 kg of a 31.0 weightpercent solution of styrene in hexanes (1.2 kg, 10.9 mol). The mixturewas stirred and heated to 32° C. When the temperature target wasreached, 61 grams of a 3 weight percent solution of n-BuLi in hexanes(1.8 g, 0.029 mol), 3.4 g of a 10 weight percent solution of2,2′-isopropylidene bis(tetrahydrofuran) in hexanes (0.0019 mol), and1.9 g of a 15 weight percent solution of potassium t-amylate in hexanes(0.0023 mol) were added. The reaction temperature reached a peak of78.4° C. within 2 hours, at which time 5.4 g (0.018 mol, 0.6 equiv)3-(1,3,-dimethylbutylidene)aminopropyltriethoxysilane (DMBAPTES) wasadded, followed by 0.62 g DPSDO (0.0029 mol, 0.1 equiv). The reactionwas stirred for 15 minutes then 4.0 g (0.014 mol, 0.5 eqiv) oftriphenylsilanol (TPS) was added and then the sample was removed fromthe reactor with 1 weight percent BHT added for oxidation protection.

Example 4

This example was prepared similar to Example 3, except 0.8 gethylsilicate was added 15 minutes after the peak of 88.3° C., followed20 minutes later by 4.3 g (0.014 mol, 0.45 equiv)3-(1,3,-dimethylbutylidene)aminopropyltriethoxysilane (DMBAPTES) wasadded. The reaction was stirred for 15 minutes then cooled and 9 kg ofcement was dropped into a pail. After dropping to the pail, 7.3 g (0.026mol, 2.0 eqiv) of triphenylsilanol (TPS) was added and 0.025 weightpercent of Santoflex™ 77(N,N′-Bis(1,4-dimethylpentyl)-p-phenylenediamine) was added foroxidation protection.

Example 5

This example was prepared similar to Example 4, except after dropping tothe pail, 3.65 g (0.013 mol, 1.0 eqiv) of triphenylsilanol (TPS) and0.57 g (0.0026 mol, 0.2 equiv) DPSDO was added and 0.025 weight percentof Santoflex™ 77 was added for oxidation protection.

Example 6

This example was prepared similar to Example 4, except after dropping tothe pail, 1.8 g (0.0063 mol, 0.5 eqiv) of triphenylsilanol (TPS) and0.57 g (0.0026 mol, 0.2 equiv) DPSDO was added and 0.025 weight percentof Santoflex™ 77 was added for oxidation protection.

Example 7

This example was prepared similar to Example 4, except after dropping tothe pail, 3.7 g (0.013 mol, 1.0 eqiv) of triphenylsilanol (TPS) and 1.14g (0.0052 mol, 0.4 equiv) DPSDO was added and 0.025 weight percent ofSantoflex™ 77 was added for oxidation protection.

As is well known in the art, polymer cement refers to polymer solutions,including polymer dissolved in a solvent, polymer suspended in asolvent, or a combination thereof. The resultant polymer samples weresteam desolventized at 180° F. (82.2° C.), then dried in an air oven at70° C. for 4 hours. The dried samples were aged at 100° C. ambient airhumidity for 2 days. Mooney viscosity (at 100° C.) was measured at 1 and2 days. The results of the Mooney viscosity tests and other testing areshown in the tables and graphs mentioned below. The accelerated polymeraging data is meant to simulate longer term storage, using a settemperature over a set period of time. In the examples, unless otherwisestated, 100° C. was used, over a period of 48 hours, in an ambient airoven.

The data described in the Table 1 shows that alone, DPSDO or TPS at lowequivalents per initiator (less than 1) results in about 70 points ofMooney growth after aging. However, if DPSDO is used in combination withanother agent (such as TPS), the Mooney growth is substantially reduced(e.g., 20 points growth, with only 0.5 mole equivalents of TPS added and0.1 mole equivalent DPSDO).

Compounding was performed according to the following formula:

Materials added phr grams MASTERBATCH Polymer (SBR, examples 7-9) 80.0121.3 Natural rubber 20.0 30.0 Carbon black 5.0 7.6 Silica 50.0 75.8Silane coupling agent 5.0 7.6 Black Oil 10.0 15.2 Stearic Acid 2.0 3.0FINAL MIX Masterbatch 172.0 252.0 Sulfur 1.5 2.2 TBBS 2.5 3.7 DPG 1.42.1 6PPD 1.0 1.5 Zinc Oxide 2.5 3.7

Materials Description:

-   -   Natural Rubber: NR20 grade, SIR20    -   Carbon Black: High structure N343, HAF    -   Silica: HISIL™ 190G precipitated silica,    -   PPG    -   Silane coupling agent: EVONIC™ Si75,        bis(triethoxysilylpropyl)polysulfide    -   Black Oil: Modified naphthenic oil, ERGON™ B0300    -   6PPD: SANTOFLEX™ 13 antioxidant        (N-1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine    -   TBBS: SANTOCURE™ NS accelerator,        N-tert-butyl-2-benzothiazolesulfenamide    -   DPG: Diphenylguanidine (accelerator)    -   phr—parts per hundred based on polymer

Mixing Procedure (Masterbatch): Into a Brabender mixer, 75 wt. % of theHISIL 190G silica, N343 carbon black and stearic acid were added andmixed for 30 seconds with the SBR polymer. At this point, the black oil,Si75 coupling agent, and the remainder of the silica, black, and stearicacid were added into the mixer. The mixture was mixed until the internaltemperature reached 170° C. or 6 minutes total time elasped. The batchwas then passed through a mill preheated to 40° C. with a ¼ inch gapfour times, folding between passes, and removed. The batch was let restfor 1 hour before the remill step was performed.

Mixing Cycle (Remill): The Brabender mixer was preheated to 90° C., thencharge with the masterbatch contents and mixed until temperature reaches150° C. The material was removed from the mixer, and the batch was thenpassed through a mill preheated to 40° C. with a ¼inch gap four times,folding between passes, and removed. The batch was let rest for 1 hourbefore the final mixing step was performed.

Mixing Cycle (Final): A Brabender mixer was preheated to 70° C., chargedwith the masterbatch rubber and the curing ingredients, and mixed untilthe temperature reaches 110° C. The material was removed from the mixer,and the batch was then passed through a mill preheated to 40° C. with a¼ inch gap four times, folding between passes, and removed. The curedrubber batch material was then sheeted out and compounded for testing.

Tan delta at 65 degrees C is a well known industry test for the measureof rolling resistance. The lower the tan delta indicates a compoundrubber with less rolling resistance, which is an important property fortires for improved fuel efficiency, etc. The data shows increasing DPDSOdecreases the tan delta at 65 degrees C which indicates, among otherthings, superior rolling resistance properties—in addition to loweringMooney growth as shown. As also demonstrated, the combination ofstabilizers described results in better properties than either onealone, and an overall lowering of the amount of stabilizing materialneeded to produce the improved properties described.

TABLE 1 Initial Dried Aged Delta Example BTMSPMA DMBAPTES TPS DPSDO ML4ML4 ML4 ML 1 0.0 0.5 0.0 0.1 36.6 54.7 105.9 69.3 2 0.1 0.6 0.42 0.077.2 96.3 148.9 71.7 3 0.0 0.5 0.5 0.1 31.5 31.3 58.4 26.9

TABLE 2 Initial Dried Aged Delta Example Ethylsilicate DMBAPTES TPSDPSDO ML4 ML4 ML4 ML 4 0.04 0.45 2 0 52.0 51.8 56.7 4.9 5 0.04 0.45 10.2 62.4 63.8 68.1 4.3 6 0.04 0.45 0.5 0.2 57.8 62 68.5 6.5 7 0.04 0.451 0.4 57.0 56.4 60.7 4.3

TABLE 3 Sample ID 0° C. TD CPD* ML 65° C. TD** Example 4 0.384 70.60.123 Example 5 0.448 80.7 0.117 Example 6 0.478 81.1 0.115 Example 70.414 77.0 0.101 *CPD = compound **TD = Tan Delta

The invention is particularly suited for alkoxysilane functionalterminated polymers, but is not necessarily limited thereto. Themoisture stabilized polymers and method of the present invention can beused separately with other equipment, methods and the like, to producevarious polymeric materials or compounds suitable for use in theproduction of various articles including pneumatic tires and the like,especially in the tread and sidewall portions of the tires, processedand made by conventional processing. Thus, the scope of the inventionshall include all modifications and variations that may fall within thescope of the attached claims. Other embodiments of the invention will beapparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein. It isintended that the specification and examples be considered as exemplaryonly, with a true scope and spirit of the invention being indicated bythe following claims.

What is claimed is:
 1. A method of making a polymer comprising, reactinga conjugated diolefin in a hydrocarbon solvent in the presence of aninitiator to form a polymer, bonding alkoxy silane terminalfunctionalizing groups to the polymer, adding a mixture of stabilizingagents to the polymer, including at least one of a first stabilizingagents having the formula (R)_(4-n)Si(OH)_(n) wherein R is a C₁ to C₁₈alkyl, C₁ to C₁₈ alkyl group containing a heteroatom such as nitrogen oroxygen, C₄ to C₈ cycloalkyl, or C₆ to C₁₈ aromatic group, and n is equalto 1, and at least one of a second stabilizing agents having the formula(R)₂Si(OH)₂ wherein R is a C₆ to C₁₈ aromatic group, and desolvatizingthe polymer, resulting in a polymer with stable Mooney viscosity.
 2. Themethod of claim 1, wherein the first stabilizing agent is atrialkylsilanol, a triarylsilanol, or mixtures thereof.
 3. The method ofclaim 1, wherein the second stabilizing agent is at least onediarylsilanediol.
 4. The method of claim 2, wherein the firststabilizing agent is triphenylsilanol.
 5. The method of claim 2, whereinthe second stabilizing agent is diphenysilanediol.
 6. The method ofclaim 1, wherein the desolvatizing is performed by drum drying, directdrying, or steam desolvatizing.
 7. The method of claim 1, wherein thestabilizing agent is added to the polymer in the presence of hydrocarbonoil.
 8. The method of claim 1, wherein the initiator is butyl lithium.9. The method of claim 1, wherein the hydrocarbon solvent is one or morehexanes.
 10. The method of claim 1, wherein the conjugated diolefin is1,3-butadiene.
 11. The method of claim 1, wherein the polymerizing stepincludes the presence of an aromatic vinyl compound.
 12. The method ofclaim 11, wherein the aromatic vinyl compound is styrene.
 13. The methodof claim 7, wherein the hydrocarbon oil is black oil.
 14. The method ofclaim 1 including drying the polymer after steam desolvatizing.
 15. Thepolymer produced by the process of claim
 1. 16. A rubber compositioncontaining a filler and the polymer of claim
 15. 17. The rubbercomposition of claim 16 having a 65° C. tan delta lower than the 65° C.tan delta of a rubber composition with either the first stabilizingagent or the second stabilizing agent used alone.
 18. A tire comprisinga sidewall and/or a tread containing the rubber of claim
 16. 19. A tirecomprising a sidewall and/or a tread containing the rubber of claim 17.